Multi-Physics Models for Proppant Placement in Energy Georeservoirs

能源地质储层支撑剂放置的多物理模型

• 批准号: 1563614
• 负责人: Ingrid Tomac
• 金额: $ 35.44万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1563614&HistoricalAwards=false
• 关键词: Multi; Physics; Models; Proppant; Placement

Underground energy technologies are of crucial importance in contemporary geomechanics, including Enhanced Geothermal Systems (EGS). EGS use geothermal energy to produce electricity from hot deep underground permeability-enhanced rock formations. This project addresses the need for more effective proppant (granular material that keeps the fractures open) usage during geothermal energy recovery. Specifically, resolving proppant placement issues will aid optimization, growth and further development of georeservoirs, and will speed up transformation of the EGS technology from its current early development stage to commercial use. This will benefit global renewable energy market and global sustainable energy delivery. This research has also a potential for contributing to quantitative understanding of several additional geomechanical issues, such as mud flows and slurry flows, internal erosion of dams and scouring of soil around structures. This research project advances the knowledge of fundamental physics of flow of dense suspensions, and develops new theories that would improve engineering design for proppant placement into branching hydraulic fractures with irregular, rough surfaces. The models resulting from this activity will, for the first time, capture particle agglomeration by accounting for the interplay between particle-particle interactions and fluid hydrodynamic forces and the role of fluid, particle and fracture properties. Our multidisciplinary team, consisting of a geotechnical engineer and a mathematical modeler, will collaborate with other programs to broaden participation of women and other underrepresented groups in science through research, engineering and educational engagements.This project seeks to better understand and mitigate the conditions resulting in proppant logging during proppant-fluid injection into hydraulic fractures. The project products will lead to efficient proppant placement during permeability enhancement, potentially reducing its environmental impact. The overarching goal of this project is to gain quantitative understanding of this phenomenon and requires development of new mathematical theories. Current practice for predicting proppant flow and transport relies on empirical relationships developed from laboratory tests involving large width, smooth, straight slots, appropriate for use in simplified single-fracture models. However, most hydraulic fractures are rough and branching, which creates a complex path for the fluid and proppant transport. The physics of dense slurry flow and transport includes particle-particle and fluid-particle interactions. Especially for fluids used in proppant placement, this physics is not properly understood and, hence, not adequately accounted for in current models. A mathematical model of proppant flow in realistic fracture networks will be developed, and validated with laboratory-scale experiments. The experimental component comprises next-generation slot-flow experiments in 3-D printed fractures using scanned rock surfaces from fracturing tests. The fractures will be printed with transparent materials, enabling the use of Particle Image Velocimetry (PIV) to track the movement of proppant particles. The project's theoretical part consists of two interrelated components, development of a continuum-scale constitutive law that accounts for particle-particle and particle-fluid interactions, and development of a computationally efficient algorithm for modeling proppant flow in fractures with rough walls and (randomly) varying apertures. The continuum-scale models will be parameterized with parameters reflecting properties of fracture surface's roughness, average fracture width, and physical and mechanical properties of fluid and proppant particles. These and other effective model parameters will be determined from both discrete numerical simulations and slot-flow experiments. The model will serve as a practical tool for reservoir engineers to ensure the proper proppant placement in hydraulic fractures and to predict and plan the reliable permeability enhancement of georeservoirs.

地下能源技术在当代地质力学中具有至关重要的意义，包括增强型地质勘探系统（EGS）。环境商品和服务利用地热能从地下深层热的渗透性增强的岩层中发电。该项目解决了在地热能回收过程中更有效地使用支撑剂（保持裂缝开放的颗粒材料）的需求。具体而言，解决支撑剂放置问题将有助于地质储层的优化、增长和进一步开发，并将加速EGS技术从其当前的早期开发阶段向商业用途的转变。 这将有利于全球可再生能源市场和全球可持续能源供应。这项研究也有可能有助于定量了解几个额外的地质力学问题，如泥浆流和泥浆流，内部侵蚀的大坝和冲刷周围的土壤结构。该研究项目推进了稠密悬浮液流动的基础物理知识，并开发了新的理论，这些理论将改善支撑剂放置到具有不规则粗糙表面的分支水力裂缝中的工程设计。该活动产生的模型将首次通过考虑颗粒-颗粒相互作用和流体水动力之间的相互作用以及流体、颗粒和裂缝性质的作用来捕获颗粒团聚。我们的多学科团队由一名岩土工程师和一名数学建模师组成，将与其他项目合作，通过研究、工程和教育活动，扩大妇女和其他代表性不足的群体在科学领域的参与。该项目旨在更好地了解和减轻在支撑剂注入水力压裂过程中导致支撑剂测井的条件。该项目产品将在渗透率提高期间有效地放置支撑剂，从而可能减少其对环境的影响。该项目的总体目标是获得对这种现象的定量理解，并需要开发新的数学理论。目前预测支撑剂流动和运输的实践依赖于从实验室测试开发的经验关系，实验室测试涉及大宽度、光滑、直槽，适用于简化的单裂缝模型。然而，大多数水力压裂裂缝是粗糙的和分支的，这为流体和支撑剂输送创建了复杂的路径。稠密浆体流动和输送的物理学包括颗粒-颗粒和流体-颗粒相互作用。特别是对于支撑剂放置中使用的流体，这种物理学没有得到正确理解，因此在当前模型中没有充分考虑。将开发现实裂缝网络中支撑剂流动的数学模型，并通过实验室规模的实验进行验证。实验组件包括使用压裂测试中扫描的岩石表面在3D打印裂缝中进行的下一代狭缝流实验。裂缝将用透明材料打印，从而能够使用粒子图像测速（PIV）来跟踪支撑剂颗粒的运动。该项目的理论部分包括两个相互关联的组成部分，一个连续尺度的本构关系，占颗粒-颗粒和颗粒-流体相互作用的发展，和开发一个计算效率高的算法，用于模拟支撑剂流动的裂缝与粗糙的墙壁和（随机）变化的孔径。将用反映裂缝表面粗糙度、平均裂缝宽度以及流体和支撑剂颗粒的物理和机械性质的参数来参数化连续尺度模型。这些和其他有效的模型参数将确定从离散数值模拟和槽流实验。该模型将作为一个实用的工具，油藏工程师，以确保适当的支撑剂放置在水力压裂，预测和规划可靠的地质油藏的渗透率提高。